Heart valve disease is a widespread condition in which one or more of the valves of the heart fails to function properly. Valve disease can be severely debilitating and even fatal if left untreated. Physicians use a variety of prostheses to correct problems associated with diseased heart valves. A typical procedure involves removal of the native valve and surgical replacement with a prosthetic heart valve.
Aortic and pulmonary heart valves are positioned at the connection of arteries to the left and right heart ventricles, respectively. Replacement or repair of these valves may involve disconnecting and reconnecting the corresponding artery. This process can involve the replacement of a portion of the artery adjacent the valve with a prosthetic conduit graft. Sometimes it is desirable to replace a portion of the artery adjacent the valve due to degeneration of the artery (e.g., aneurysm) even if there is no damage to the valve. On the other hand, the standard surgical approach in patients with ascending aortic aneurysm involving the aortic root and associated aortic valve disease is the replacement of the aortic valve and ascending aorta with a composite valved graft as originally described by Bentall and de Bono in their classical paper (Bentall H. H., De Bono A.: A technique for complete replacement of the ascending aorta, Thorax 1968; 23: 338-9). The ascending aorta adjacent the aortic heart valve connects to coronary arteries that provide aerated blood to the heart muscle, and thus replacement of the ascending aorta involves reconnection of the coronary arteries.
Both the natural aorta and the pulmonary artery have slightly dilated portions adjacent the heart valves called sinuses of Valsalva. The natural sinuses of the aorta are somewhat larger than the sinuses of the pulmonary artery. The aortic sinus portion has three sinuses (bulges) which surround the aortic valve, into two of which open ostia of the coronary arteries. These are called sinuses of Valsalva and are arranged so that the cross-section of the sinus portion has a generally trefoil shape. The diameter and orifice area of the root are greater at the level of the sinus, decrease slightly at the base, but significantly decrease (by 20%) at the level of the sinotubular junction or sinus ridge (where the sinus portion connects to the ascending portion of the aorta which supports the two iliac arteries). The sinotubular junction and the sinuses of Valsalva are considered important to the normal function of the aortic valve. Accordingly, conduit grafts whether valved or not often have lower bulges that simulate the sinuses of Valsalva, though straight tubes without this sinus component are also used.
A number of composite aortic valves and conduit grafts are known in the art, including in U.S. Pat. No. 5,123,919 to Sauter; U.S. Pat. No. 5,139,515 to Robicsek; U.S. Pat. No. 6,352,554 to De Paulis, and others. Vascutek, Ltd. of Inchinnan, Scotland, a division of Terumo of Tokyo, Japan, manufactures several conduit grafts for the ascending aorta, including the BioValsalva porcine aortic biological valved conduit which combines a Triplex Valsalva conduit graft with an Elan porcine stentless biological valve (Koehler, Bellshill, Scotland). The Valsalva conduit graft includes an outwardly-bulged sinus region at its proximal end which mimics the diameter of the natural sinuses. The BioValsalva valved conduit can also be made with Vascutek's Biplex conduit graft which has only two layers—an inner woven polyester and an outer self-sealing elastomer, or with Vascutek's Triplex conduit graft which has three layers—an inner polyester layer, a central self-sealing elastomeric membrane and an outer layer of ePTFE. Another Vascutek graft used is the Gelweave which includes a three layer wall construction of an inner woven polyester, a central elastomeric (gelatin) membrane and an outer ePTFE wrap.
The procedure for implanting an aortic conduit graft, with or without a valve, involves first excising the diseased portion of the ascending aorta, and aortic valve if necessary. The lower end of the conduit graft is then sewn to the valve root above the valve remnant, or the prosthetic aortic valve is sewn to the annulus, and the locations where the coronary arteries meet the sinus region of the conduit graft are marked. Two holes are burned with a cautery device into the side of the conduit graft, and the coronary artery buttons are sewn to the side of the graft at the holes. Typically, at the time of the positioning the combined aortic valve and conduit graft, the surgeon determines whether the coronary arteries have sufficient length to reach the holes made in the conduit graft, and if not, an additional tubular coronary extension segment is added to one or both of the ends of the coronary arteries so that they are not stretched and kinked. Sometimes the native sinuses bulge outward quite far, and the replacement graft is not shaped the same resulting in a gap between the coronary buttons and the side of the graft. This procedure is extremely time-consuming, and thus detrimental to the overall surgery. Finally, the upper end of the conduit graft is anastomosed to the ascending portion of the aorta. The entire process is accomplished while the patient is on cardiopulmonary bypass, and can be fairly time-consuming, especially if the coronaries require lengthening with graft segments.
There is thus a need for devices and methods that reduce the time required to secure a composite aortic valve and conduit graft.